Composite sector gear and method for manufacturing same

Abstract

A cast composite sector gear including a hub made of a first material and an outer gear section made of a second material that is cast onto the hub. The hub is configured such that a secure mechanical bond can be created between the hub and the gear section when the gear section is cast onto the hub. The hub includes a base having a peripheral surface and a gear foundation that extends circumferentially from the peripheral surface about a portion of the base. The gear section is cast onto the gear foundation, and the gear section extends circumferentially about a portion of the hub.

I claim: 
     
       1. A composite sector gear comprising: a hub made of a first material, said hub including a generally annularly shaped base which includes an outer peripheral surface, said hub further including a gear foundation which radially extends about less than the entire outer peripheral surface of said base, said gear foundation including at least one lug and opposing end stops, said hub further including a pair of outwardly extending outer faces which at least partially define said gear foundation; and   a gear section cast onto said gear foundation of said hub such that said gear section envelopes said lug and is disposed between said end stops, said gear section having a pair of spaced apart ends such that said ends are generally coplanar with said respective outer faces, and said gear section being made of a second material different from said first material.   
     
     
       2. A composite sector gear as in claim 1, wherein said first material is iron and said second material is bronze. 
     
     
       3. A composite sector gear as in claim 1, wherein said gear foundation includes an inner peripheral surface, and each end stop includes an inner face such that each end stop inner face forms an obtuse angle with said gear foundation peripheral surface. 
     
     
       4. A composite sector gear as in claim 3, wherein each obtuse angle is about 135 degrees. 
     
     
       5. A composite sector gear comprising: a hub including a base having a peripheral surface and a gear foundation that extends circumferencially from the peripheral surface about less than the entire peripheral surface of said base, said gear foundation including at least one lug and opposing end stops, said gear foundation further including a pair of spaced apart outer faces, said hub being made of a first material; and   a gear section cast onto said gear foundation such that said gear section envelopes said lug, said gear section having a pair of spaced apart ends, and said gear section extending circumferencially about a portion of said hub such that said ends are generally coplanar at said respective outer faces, said gear section being made of a second material different from said first material.   
     
     
       6. A composite sector gear as in claim 5, wherein said first material is iron and said second material is bronze. 
     
     
       7. A composite sector gear as in claim 5, wherein said gear foundation includes an inner peripheral surface, and each end stop includes an inner face such that each end stop inner face forms an obtuse angle with said gear foundation peripheral surface. 
     
     
       8. A composite sector gear as in claim 7, wherein each obtuse angle is about 135 degrees. 
     
     
       9. A composite sector gear prepared by a method comprising the steps of: providing a hub made of a first material, said hub including a generally annularly shaped base which includes an outer peripheral surface, and said hub further including a gear foundation which radially extends about less than the entire outer peripheral surface of said base, said gear foundation including at least one lug and opposing end stops, said hub further including a pair of outwardly extending spaced apart outer faces which at least partially define said gear foundation; and   casting onto said gear foundation of said hub a gear section made of a second material different from said first material such that said gear section envelopes said lug and between said end stops, said gear section having a pair of spaced apart ends which are respectively generally coplanar with said outer faces.   
     
     
       10. A composite sector gear as in claim 9, wherein said hub includes iron and said gear section includes bronze, and said casting step includes sand casting said bronze gear section onto said iron hub. 
     
     
       11. A composite sector gear as in claim 9, wherein said casting step includes: placing said hub in a casting mold having a cavity therein such that a portion of said cavity is left open, and a portion of said hub is exposed to said open portion of said cavity;   orienting said mold and said hub such that molten material may be poured into the open portion and such that air and impurities can escape from said cavity as molten material is poured into said cavity;   pouring molten material into said open portion, said molten material being different from said first material;   allowing said molten material to harden to form a mechanical bond with said hub.   
     
     
       12. A composite sector gear as in claim 9, further providing that said gear foundation includes an inner peripheral surface, and each end stop includes an inner face such that each end stop inner face forms an obtuse angle with said gear foundation peripheral surface. 
     
     
       13. A composite sector gear as in claim 12, further providing that each obtuse angle is about 135 degrees. 
     
     
       14. A composite sector gear prepared by a method comprising the steps of: providing a hub made of a first material, said hub including a base which includes a peripheral surface and a peripherally extending gear foundation that extends about less than the entire peripheral surface of of said base, said gear foundation including at least one lug and opposing end stops, said gear foundation further including a pair of spaced apart outer faces; and   casting onto said gear foundation a gear section having a pair of spaced apart ends and made of a second material different from said first material such that said gear section envelopes said lug between said end stops, and such that said ends are generally coplanar with said respective outer faces.   
     
     
       15. A composite sector gear as in claim 14, wherein said casting step is performed through sand casting. 
     
     
       16. A composite sector gear as in claim 14, wherein said casting step includes: placing said hub in a sand casting mold having a cavity therein such that said gear foundation is exposed to an open portion of said cavity;   orienting said mold and said hub such that air and impurities can escape from said open portion as molten material is poured into said open portion;   pouring molten material into said open portion, said molten material being different from said first material;   allowing said molten material to harden to form a mechanical bond with said gear foundation.   
     
     
       17. A composite sector gear as in claim 16, wherein prior to said placing step, further includes the steps of: pre-heating the hub, and   depositing a coating of carbon on the hub.   
     
     
       18. A composite sector gear as in claim 14, further providing that said gear foundation includes an inner peripheral surface, and each end stop includes an inner face such that each end stop inner face forms an obtuse angle with said gear foundation peripheral surface. 
     
     
       19. A composite sector gear as in claim 18, further providing that each obtuse angle is about 135 degrees. 
     
     
       20. A method for producing a composite sector gear comprising the steps of: providing a hub made of a first material, said hub including a generally annularly shaped base which includes an outer peripheral surface, and said hub further including a gear foundation which radially extends about less than the entire outer peripheral surface of said base, said gear foundation including at least one lug and opposing end stops, said hub further including a pair of outwardly extending spaced apart outer faces which at least partially define said gear foundation; and   casting onto said gear foundation of said hub a gear section having a pair of spaced apart ends and made of a second material different from said first material such that said gear section envelopes said lug between said end stops, and such that said ends are generally coplanar to said respective outer faces.   
     
     
       21. A method as in claim 20 wherein said casting step includes the steps of: placing said hub in a casting mold having a cavity therein such that a portion of said cavity is left open and a portion of said hub is exposed to said open portion of said cavity;   orienting said mold and said hub such that air and impurities can escape from said open portion as molten material is poured into said open portion;   pouring molten material into said open portion, said molten material being different from said first material;   allowing said molten material to harden to form a mechanical bond with said hub.   
     
     
       22. A method as in claim 21 wherein said casting step further includes, prior to said placing step, the steps of: pre-heating the hub, and   depositing a coating of carbon on the hub.   
     
     
       23. A method as in claim 20, wherein said gear foundation further includes an inner peripheral surface, and each end stop includes an inner face such that each end stop inner face forms an obtuse angle with said gear foundation peripheral surface. 
     
     
       24. A method as in claim 23, further providing that each obtuse angle is about 135 degrees. 
     
     
       25. A composite sector gear comprising: a hub made of a first material, said hub including a base and a peripherally extending gear foundation that extends about a portion of said base, wherein said gear foundation includes an inner peripheral surface and at least one lug and opposing end stops, wherein each end stop includes an inner face such that each end stop inner face forms an obtuse angle with said gear foundation peripheral surface; and   a gear section cast onto said hub, said gear section having a pair of spaced apart ends, said gear section being made of a second material different from said first material, wherein said gear foundation supports said gear section, and wherein a portion of said gear section envelopes said lug and is disposed between said end stops.